After an average of 27 years' follow-up of patients with type 1 diabetes, 6.5 years of initial intensive diabetes therapy was associated with a modestly lower all-cause rate of death, compared with conventional therapy, according to a study in the January 6 issue of JAMA.
Based on the demonstrated reductions in illness, intensive diabetes therapy is now the recommended standard of care; however, it has not been established whether mortality in type 1 diabetes mellitus is affected following a period of intensive diabetes therapy. In type 2 diabetes treatment, reducing glycemia (blood sugar) closer to the nondiabetic range has not consistently reduced mortality, according to background information in the article.
Trevor J. Orchard, M.D., of the University of Pittsburgh, and colleagues examined whether mortality differed between the original intensive and conventional treatment groups in the long-term follow-up of the Diabetes Control and Complications Trial (DCCT) cohort. The DCCT (1983-1993) randomly assigned 1,441 healthy volunteers with type 1 diabetes mellitus between the ages of 13 and 39 years to intensive or conventional therapy, with the goal of studying the effects of near-normal blood sugars on long-term diabetes complications. After the DCCT ended, participants were followed up in a multisite (27 U.S. and Canadian academic clinical centers) observational study (Epidemiology of Diabetes Interventions and Complications; EDIC) until December 31, 2012.
During the initial clinical trial, participants were randomly assigned to receive intensive therapy (n = 711) aimed at achieving blood sugar control as close to the nondiabetic range as safely possible, or conventional therapy (n = 730) with the goal of avoiding symptomatic hypoglycemia (abnormally low blood sugar) and hyperglycemia (abnormally high blood sugar). At the end of the DCCT, after an average of 6.5 years, intensive therapy was taught and recommended to all participants and diabetes care was returned to personal physicians.
Vital status was ascertained for 1,429 (99.2 percent) participants. Of the 107 (7.4 percent) deaths, 43 (6.0 percent) were in the intensive treatment group and 64 (8.8 percent) were in the conventional treatment group. Overall mortality risk in the intensive group was lower than that in the conventional group, although the absolute risk reduction was small.
Primary causes of death were cardiovascular disease, cancer, acute diabetes complications, and accidents or suicide. Higher levels of glycated hemoglobin (a common lab test that gauges overall blood sugar control) were associated with all-cause mortality, as well as the development of albuminuria (the presence of excessive protein in the urine).
The authors write that intensive therapy is associated with increased hypoglycemic risk, which in turn has been associated with increased mortality. "The current data suggest net mortality benefit from intensive therapy ... These results provide reassurance that adoption of 6.5 years of intensive therapy in type 1 diabetes does not incur increased risk of overall mortality."
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